Python virtual environments are used to create isolated python environments to avoid dependency and version conflicts, and also indirectly take care of permission issues. But what is the easiest way to set it up, and use it, in Ubuntu?
virtualenvwrapper (user friendly wrappers for the functionality of
sudo apt install virtualenv
The reason we are also installing virtualenvwrapper is because it offers nice and simple commands to manage your virtual environments. There are two ways to install
As Ubuntu package (from Ubuntu 16.04)
sudo apt install virtualenvwrapper
echo "source /usr/share/virtualenvwrapper/virtualenvwrapper.sh" >> ~/.bashrc
Install and/or update pip
Install pip for Python 2 with
sudo apt install python-pip
or for Python 3
sudo apt install python3-pip
(if you use Python 3, you may need to use
pipin the rest of this guide).
Optional (but recommended): Turn on bash autocomplete for pip
pip completion --bash >> ~/.bashrc
source ~/.bashrcto enable.
Because we want to avoid
sudo pipwe install
virtualenvwrapperlocally (by default under
pip install --user virtualenvwrapper
echo "export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3" >> ~/.bashrc
Source virtualenvwrapper in
echo "source ~/.local/bin/virtualenvwrapper.sh" >> ~/.bashrc
Setup virtualenv and virtualenvwrapper:
First we export the
WORKON_HOME variable which contains the directory in which our virtual environments are to be stored. Let's make this
now also create this directory
and put this export in our
~/.bashrc file so this variable gets automatically defined
echo "export WORKON_HOME=$WORKON_HOME" >> ~/.bashrc
We can also add some extra tricks like the following, which makes sure that if
pip creates an extra virtual environment, it is also placed in our
echo "export PIP_VIRTUALENV_BASE=$WORKON_HOME" >> ~/.bashrc
Source ~/.bashrc to load the changes
Test if it works
Now we create our first virtual environment. The
-p argument is optional, it is used to set the Python version to use; it can also be
python3 for example.
mkvirtualenv -p python2.7 test
You will see that the environment will be set up, and your prompt now includes the name of your active environment in parentheses. Also if you now run
python -c "import sys; print sys.path"
you should see a lot of
/home/user/.virtualenv/... because it now doesn't use your system site-packages.
You can deactivate your environment by running
and if you want to work on it again, simply type
Finally, if you want to delete your environment, type
Thanks to the author of this blogpost.
Virtual environments offer a way for managing and isolating dependencies on a per-project basis. Moreover, they also avoid the whole
sudo pip install situation, which is a security risk as I have explained in https://askubuntu.com/a/802594/15003. The official Python documentation also encourages the use of virtual environments.
The easiest way to create and use virtual environments for both Python 2 and Python 3 is to install
apt-get. For each Python project, create a virtualenv and then activate it. Note that the virtualenv is specific for a particular Python version. After activation, use
pip to install Python packages as usual regardless of whether you are using Python 2 or 3; there is no need to use
pip3 for Python 3.
sudo is only used to install
virtualenv and is not used with
pip, therefore avoiding the aforementioned security risk. The commands to do so are:
sudo apt update
sudo apt install virtualenv
cd ~/desired_directory # cd to desired_directory
virtualenv venv # create virtualenv named venv for default system Python, which is Python 2 for Ubuntu
source venv/bin/activate # activate virtualenv
pip install -U pip # upgrade pip in case it is outdated
pip install desired_package # install desired_package
If you would like to create a virtualenv for Python 3, replace
virtualenv venv with:
virtualenv venv -p python3
Read more about various bells and whistles for
virtualenv at https://virtualenv.pypa.io/en/stable/.
With the venv module available from Python 3.3 (and Ubuntu 15.10)
Virtual environments (venvs) are so popular that the functionality is now included in python itself (from 3.3 onwards). To use it on Ubuntu you need to install
python3-venv (since the
ensurepip module is not available):
sudo apt-get install python3-venv
After that you can use
to create a virtual environment called
myvirtualenv. You can then use
to activate the virtual environment. To deactivate simply type
pyvenv script has been deprecated in favour of
python3 -m venv. This prevents confusion as to what Python interpreter
pyvenv is connected to and thus what Python interpreter will be used by the virtual environment. (source)